In his U.S. Pat. No. 4,082,296, issued in the United States on Apr. 4, 1978, P. Charles Stein provided a plurality of embodiments of sealing members for sealing between a rotating member and a housing. The sealing members were provided in one embodiment in the form of a segmented seal ring resiliently mounted about a shaft or a sleeve mounted on the shaft to move toward and away from the shaft to provide a seal therebetween. The seal ring is segmented by providing a plurality of circumferential segments end to end to form the seal ring and such that a seal is also effected in the radial direction between each segment. In the circumferential sealing face of each segment of the seal ring adjacent the shaft, predetermined precise grooves are provided which produce a negative hydrodynamic lift force and urge the seal ring segments toward the rotating shaft in order to reduce leakage thereacross. Thus, during shaft rotation, the medium in which the seal is operating, e.g. oil, water or gas, is swept out of the sealing grooves through an axially disposed communication port by a pumping action to provide the negative hydrodynamic lift force and to move the seal ring toward the shaft to effectuate greater sealing. Thus, the pressure in the grooves of the sealing faces of the sealing ring during shaft rotation is lower than system pressure.
The seal in the radial direction between each seal segment is formed between a tongue portion of the seal segment at the end of the face groove remote from the axial communication port thereof which is received in a complementarily-shaped groove formed in the adjacent end of the adjacent seal ring segment. In certain applications, especially when the seal is operating in a pressurized oil mist atmosphere, pressure tends to build up in the space between the tongue of one segment and the complementary groove in the adjacent segment. This pressure build-up, if sufficient, could result in leakage along the radial path between adjacent segments. The purpose of this invention is to provide a modification of the Stein seal ring arrangement for use with rotatable shafts to overcome this objection to the seal ring design. The potential axial leakage problem which may occur is solved by this invention.